Reference#: P01408

Cooling towers, which are an inexpensive and environmentally friendly method to control process and building temperatures, require the addition of anti-fouling and corrosion inhibiting chemicals. PBTC (2-phosphonobutane 1,2,4 tricarboxylic acid) and HEDP (hydroxy ethylidene diphosphonic acid) are the main anti-cladding and corrosion inhibitors used in the United States. As yet, there is no reliable and inexpensive electronic monitoring device to allow each building to determine when additional PBTC/HEDP is required. Conventional technology relies on manual chemical analysis and/or batch replenishments of the additives.

The Johns Hopkins Applied Physics Lab has developed molecularly imprinted polymers (MIP), a class of synthetic polymers that may be tailored to selectively detect a particular substance. The molecular imprinting technique involves a polymer, which has been synthesized in the presence of a target molecule, being used to separate a target molecule from other species. The polymers are constructed with ligands to contain cavities which closely match the shapes of various analyte molecules. The analyte molecules are incorporated into a pre-polymeric mixture and allowed to form bonds with the pre-polymer. The mixture is then polymerized with the analyte molecules in place. Once the polymer has formed, the analyte molecules are removed, leaving behind cavities with the analyte molecule's shape. In this way, a particular molecule can be identified since the shape of the cavity is specific to the molecule modeled. This method of identifying a particular molecule is attractive because of the simplicity of the preparation of the polymer and the simplicity and specificity of the identification of a target molecule.

APL has developed this invention to provide a molecularly imprinted polymeric sensor that will allow for unambiguous monitoring of PBTC and HEDP in a complex industrial water matrix (Ca +2, Mg +2, Cl-, SO4-2, HCO3- and carboxylate and sulfonate containing polymers). This MIP sensor can be incorporated into an inexpensive electronic unit based on an immobilized lanthanide transducer that will employ MIP and lanthanide luminescence in combination for extremely high chemical selectivity. In the simpler form, the unit will provide a warning light when the concentration falls below a level recommended by the additive supplier. In a more robust unit, changes in PBTC/HEDP levels can trigger electronic circuits and metering valves to automatically add the proper amount of additives.